Unsaturated substituted cyclic sulfones and process for preparing the same



United States Patent 3,192,231 UNSATURATED SUBSTITUTED CYCLE: SUL- ANDPROCESS FOR PREPARING THE Richard Parke Welcher, Old Greenwich, Conn,assignor 'to American Cyanamid Company, Stamford, Conn, a

corporation of Maine No Drawing. Filed Sept. 19, 1962, Ser. No. 224,85911 Claims. (Cl. 260-3321) This invention relates to novel unsaturatedsubstituted cyclic sulfones and to a process for preparing the same. Ina more particular aspect, this invention relates to novel unsaturatedcyclic sulfones having one to four substituent groups on the carbonatoms adjacent to the sulfur atom, .that is, on the alpha carbon atoms,and to a process for preparing the same. In a still more particularaspect, this invention relates to novel unsaturated substituted cyclicsulfones of the formula:

7 S Re o o in which the substituents R R R and R are each selected fromthe group consisting of hydrogen, alkyl, alkenyl, aryl, alkaryl,aralkyl, cycloalkyl, cycloalkenyl, and cyanoethyl with the proviso thatat least one of the R R R and R .substituents is cyanoethyl and R and Rare each selected from the group consisting of hydrogen, alkyl, alkenyl,aryl, alkaryl, aralkyl cycloalkyl, and cycloalkenyl. From the structuralrepresentation of the novel compounds of the present invention, it willbe seen that the unsaturated substituted cyclic sulfones of thisinvention may also be described as 3-sulfolenes having at least onecyanoethyl grouping attached to the 2- or S-nuclear carbon atom.

While aryl sulfones have been known to be capable of undergoingcyanoethylation, the cyanoethylation of unsaturated cyclic sulfones hasnot previously been described. While it should be mentioned that O.Bayer, Angew. Chem. 61, 229 (1949), reported the unpublished study of R.Wegler and H. Lafos of the cyanoethylation of sulfones, it is observedthat the there described condensation of acrylonitrile with a typicalunsaturatedcyclic sulfone, i.e., butadiene sulfone, afforded notdefinite crystalline products but instead higher molecular weightcondensation products which were recovered only upon distillation underhigh vacuum. Bayer concluded that the possibility of reaction of amaximum of four moles of acrylonitrile with one mole of butadiene.sulfone seemed unlikely. The author further stated that it was believedthat the acrylonitrile was caused to polymerize under basic conditionsso as to produce, in addition to higher molecular weigh-t products, asubstance having an analysis corresponding to a ratio of three moles ofacrylonitrile to one mole of butadiene sulfone, which may be possiblyconsidered polyacrylonitnle of short chain length terminating in a dienesulfone unit. In view, therefore, of Bayers report, it was indeedsurprising and unexpected to find that unsaturated cyclic sulfones, thesimplest member of the class being butadiene sulfone, could be reactedwith acrylonitrile so as to readily yield unsaturated cyclic sulfoneshaving at least one cyanoethyl substituent in either the 2- or'5-nuclear carbon position with definitely defined physicalcharacteristics, i.e., solids having sharp melting points or, in certaincases, liquids with reproducible refractive ind-ices, good agreementwith theoretical elemental analysis and theoretical molecular weight,etc.

In accordance with the present invention, it has been discovered thatnovel unsaturated substituted cyclic sulfones having the formula asdefined hereinabove may be readily prepared by reacting in the presenceof an alkaline condensing agent acrylonitrile and an'unsaturated cyclicsulfone of .the'formula:

in which R to R inclusive, are each selected from the group consistingof hydrogen, alkyl, alkenyl, aryl, alk-aryl, aralky-l, cycloalkyl, andcycloalkenyl, with the proviso that at least one of R R R or R ishydrogen. By this reaction, the 2- or S-carbon atom or both iscyanoethylated. Thus, the novel compounds of this invention may containone, two, three or four cyanoethyl (CH CH CN--) groups depending uponthe absence of hydrocarbon substituents as values for R R R and R in thestarting sulfone. The only critical limitation in the carrying out ofthe process for producing the novel compounds of this invention is thatfunctional groups should not be present on the R to R inclusive,substituen-ts of the starting .sulfone which would undergo sidereactions either with the basic catalyst or with acrylonitrile itself.Thus, :substituents for R to R inclusive, containing halogen atoms,carbonyl groups and the like are precluded.

For effecting cyanoethylation of the unsaturated cyclic sulfones,alkaline condensing agents of a broad class may be readily employed.Thus, oxides, hydroxides, amides, hydrides or alcohola-tes of the alkalimetals or the alkali metals themselves or strongly basic quaternaryammonium hydroxides may be used. Also, organic bases, such asheptamethylbiguanide, which are themselves not attacked by acrylonitrilemay also be used. Typical con I densing agents are sodium or potassiumoxide, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodiumamide, potassium hydride, potassium ethylate, benzyl trimethyl ammoniumhydroxide, dibenzyl dimethyl ammonium hydroxide or the like. Generally,small amounts of such alkaline condensing agents are required, about 1to 10 mole percent of the unsaturated cyclic sulfone usually beingsufficient.

If desired, the cyanoethylation reaction may be carried out in thepresence of a solvent which is inert or which is less reactive withacrylonitrile than the unsaturated cyclic sulfone. Ordinarily, the useof a solvent is preferred. Typical solvents which serve as suspendingmedia, diluents or actual solvents for the reactants and,

alkaline condensing agent are aromatic hydrocarbons such as benzene,toluene and the like, dioxane, dimethylformamide, tertiary butylalcohol, acetonitrile, etc. Usually, acetonitrile is the solvent ofchoice.

In order to forestall possible polymerization of acrylonitrile duringthe course of the reaction, a polymerization inhibitor such as tertiarybutyl catechol, hydroquinone, naphthylamine, etc. may be employed andmay be added to the reaction mass together with the acrylonitrilereactant.

The reaction of an unsaturated cyclic sulfone with acrylonitrile in thepresence of an alkaline condensing agent may be effected at temperaturesbetween about 20 C. and up to about 100 C. Even higher temperatures arenot precluded but such temperatures will be limited only by the boilingpoint of the acrylonitrile-solvent mixture. Preferably, temperatures offrom about 10 C. to about C. are employed. Since the cyanoethylationreaction is ordinarily exothermic, it is generally desirable to controlthe resulting rise in temperature by external cooling, rate of mixing orother conventional means. i

The reactants need not be mixed with one another in Patented June 29,1965 I any particular order. Thus, the unsaturated cyclic sulfone may beadded to acrylonitrile or vice versa or the reactants may besimultaneously added to the reaction vessel. The condensing agent may beinitially present in the reaction vessel or it may be added after thesulfone reactant has been mixed with acrylonitrile.

The molar ratio of reactants, that is, unsaturated cyclic sulfone andacrylonitrile, is generally determined by the degree of cyanoethylationdesired in the final product. Thus, for the obtaining of monocyanoethylsubstituted sulfones, approximately equimolecular quantities of sultoneand acrylonitrile are employed. It is frequently desirable' to use anexcess quantity of sulfone. Even then, however, polycyanoethylatedproducts may be obtained inaddition to the monocyanaoethylated product.When dicyanoethylated, tricyanoethylated and tetracyanoethylatedproducts are desired, a two-fold, three-fold, or fourfold molar quantityof acrylonitrile is employed. Here again, however, cyclic sulfoneshaving higher degrees of cyanoethylation may be obtained. In any event,either the unsaturated cyclic sulfone or acrylonitrile may be used inexcess depending upon the product desired.

While the reaction is ordinarily carried out at atmospheric pressure,higher pressures are not precluded from use. Thus, elevated pressuresmay be employed in order to use reaction temperatures above the boilingpoint of the acrylonitrile-solvent mixture.

Following the completion of the reaction or when the reaction has beencarried to the desired stage, it is usually recommended to destroy orremove the alkaline condensing agent by neutralizing it, extracting it,or otherwise disposing of it. The reaction product is then isolated in aconventional manner, for example, by filtration, distillation ofsolvent, selective extraction, selective adsorption or the like.

Any of a broad class of unsaturated cyclic sulfones, unsubstituted andsubstituted, may be employed in the process of this invention. Suchsulfones are sometimes commonly referred to as 3-sulfolenes, that ia, afive-membered ring of four carbon atoms and a sulfur atom with a singleolefinic linkage between the two and three carbon atoms of said ring andtwo oxygen atoms, both of which are attached directly to the sulfur atomtherein. In addition to being describd as 3-sulfolenes, th unsaturatedcyclic sulfones suitablefor use in the process of this invention may bealso described in accordance, with another type of monenclature. Thus,the simplest sulfone, butadiene sulfone, is namedlzl-dioxythiacyclopent-3- ene. Such unsaturated cyclic sulfones arereadily obtained by'the reaction of sulfur dioxide with butadiene andits homologs and analogs. Butadiene, its homologs or analogs all ofwhich may be described by the formula:

in which the substituents R to R inclusive, are as defined hereinabovefor the starting sulfones may be converted to the corresponding cyclicsulfones by reaction with sulfur dioxide in a known manner. In additionto butadiene-1,3-, the simplest diene reactant, other aliphaticpolyolefins which afford unsaturated cyclic sulfones suitable for use inthis invention include Z-methyl butadiene- 1,3 (isoprene);pentadiene-1,3 (piperylene); 1,3-dimethyl butadiene-1,3; 2,3-dimethylbutadien -1,3; 2,3-diethyl butadiene-1,3; 2,3-ditertiary-butylbutadiene-1,3; 2-tertiary-butyl butadiene-1,3; 1,2,3,4-tetramethylbutadiene- 1,3; 1,4-dimethyl-2,3-diethyl butadiene-1,3; 2-methylpentadiene-1,3;4-methyl pentadiene-1,3; 2-methyl hexadiene- 1,3; 4-ethylhexadiene-1,3; hexadiene-2,4; and the like and their homologs andanalogs. The straight chain polyolefins of the class described above mayalso have alkenyl, cycloalkyl, cycloalkenyl and/or aromatic radicalslinked to carbon atoms of primary, secondary and/ or tertiary character,examples of such compounds being cyclo- 4 pentyl butadienes;cyclopentenyl butadienes; cyclopentyl pentadienes; cyclohexylbutadienes; cyclohexenyl butadienes; l-phenyl butadiene-1,3;1,2-diphenyl butadiene-1,3; Z-phenyl butadiene-1,3; 2,3-diphenylbutadiene-1,3; hexatriene-l,3,5; and the likeand their homologs andanalogs.

Thus, typical sulfones useful in the process of this invention areincluded in the following non-limiting listing: butadiene sulfone,piperylene sulfone, isoprene sulfone, 2,4-hexadiene sulfone, Z-ethylbutadiene-1,3 sulfone, 2- methyl-pentadiene-1,3 sulfone, andtheir"homologs, as well as other sulfone compounds'in which hydrocarbonradicals, such as methyl, ethyl, vinyl, propyl, isopropyl, propenyl,allyl, isopropenyl, butyl, isobutyl, butenyl, isobutenyl, pentenyl,amyl, hexyl, isohexyl, isohexenyl, cyclobutyl, cyclopentyl, cyclohexyl,cyclopentenyl, cyclohexenyl, phenyl, benzyl, tolyl, xylyl and other likeradicals are substituted for one or more of the, hydrogen atoms of theunsubstituted cyclic sulfone compounds.

The unsaturated substituted cyclic sulfones of this invention areparticularly useful in the production of synthetic resinous materials.In addition, the compounds are of value as plasticizers for variouspolymeric materials, for example, homopolymers and copolymers ofacrylonitrile and the like. The compounds may be pyrolyzed to yieldsubstituted 1,3-butadienes which are described and claimed in mycopending application Serial No. 224,861, filed concurrently herewith.

In order to further illustrate the nature of this invention, thefollowing non-limiting examples are presented.

Example 1 A solution of 11.8'parts (0.100 mole) of butadiene sulfone,23.3 parts (0.440 mole) of acrylonitrile and 20 parts of-acetonitrile isadded to a mixture of 2 parts of Triton B (benzyltrimethylammoniumhydroxide, 40% in methyl alcohol) in 20 parts of acetonitrile dropwiseover a period of 1.2 hours at 07 C. The mixture, after warming to 25 C.,is'neutralized with acetic acid and filtered. After recrystallizationfrom acetonitrile the 2,2, 5,5 thiophenetetrapropionitrile 1,1 dioxidemelts at 209.5-21'0" C., decomposing with evolution of gas.

Analysis.Calculated for C H N O S: C, 58.16; H, 5.49; N, 16.96; S, 9.70.Found: C, 58.40; H, 5.72; N, 17.53; S, 9.57.

Its infrared spectrum is consistent with the postulated structure.

Example 2 The procedure of Example 1 is repeated in all essentialrespects except that 10.6 parts (0.200 mole) of acrylonitrile is used. Asmall amout of insoluble 2,2,5,5-thiophenetetrapropionitrile-1,l-dioxideand a mixture of 2,2- thiophenedipropionitrile-1,l-dioxide and2,2,5-thiophenetripropionitrile-1,1-dioxide are obtained. The threeproducts are separated by selective extraction.

Example 3 The procedure of Example 1 is repeated in all essentialrespects except that 5.3 parts (0.100 mole) of acuylonitrile is used.2-thiophenepropionitrile-1,l-dioxide is obtained.

Example 4 The procedure of Example 1 is repeated in all essentialrespects except that isoprene sulfone is employed in place of butadienesulfone. ,3-methyl-2,2,5,5-thiophenetetrapropionitrile-l,l-dioxide isobtained.

Example 5 The procedure of Example 1 is repeated in all essentialrespect except that piperylene (2,4-pentadiene) sulfone is employed inplace. of butadiene sulfone and 15.9 parts (0.300 mole) of acrylonitrileis used. 2-methyl-2,5,5- thiophenetripropionitrile-l, l-dioxide isobtained.

Example 6 The procedure of Example 1 is repeated in all essentialrespects except that 2,4-hexadiene sulfone is employed in place ofbutadiene sulfoneand 10.60 parts (0.200 mole) of acrylonitrile is used.2,5-dimethyl-Z,S-thiophenedipropionitrile-1,1-dixide is obtained.

Example 7 The procedure of Example 1 is repeated in all essentialrespects except that 1,4-dipheny1butadiene sulfone is employed in placeof butadiene sulfone and 10.6 parts (0.200 mole) of acrylonitrile isused. 2,5-diphenyl-2,5-thiophenedipropionitrile-l,l-dioxide is obtained.

Example 8 The procedure of Example 1 is repeated in all essentialrespects except that 2,3-diphenylbutadiene sulfone is emploed in placeof butadiene sulfone. 3,4-diphenyl-2,2,5,5-thiophenetetrapropionitrile-1,l-dioxide is obtained.

While the present invention has been described in conjunction withvarious preferred embodiments, it is to be understood that the inventionis not be limited to such exemplary description but is to be construedbroadly and limited only by the following claims.

I claim:

1. An unsaturated substituted cyclic sulfone of the formula:

in which R ,R R and R are each selected from the group consisting ofhydrogen, lower alkyl, phenyl and cyanoethyl with the proviso that atleast one of the R R R and R substituents is cyanoethyl and R and R areeach selected from the group consisting of hydrogen, lower alkyl andphenyl.

2. A process for preparing an unsaturated substituted cyclic sulfone ofthe formula:

in which R R R and R are each selected from the group consisting ofhydrogen, alkyl, alkenyl, aryl, alkaryl,

aralkyl, cycloalkyl, cycloalkenyl, and cyanoethyl with the proviso thatat least one of the R R R and R substituents is cyanoethyl and R and Rare each selected from the group consisting of hydrogen, alkyl, alkenyl,aryl, alkaryl, aralkyl, cycloalkyl, and cycloalkenyl which comprisesmixing acrylonitrile and an unsaturated cyclic sulfone of the formula:

in which R to R inclusive, are each selected from the group consistingof hydrogen, alkyl, alkenyl, aryl, alkaryl, aralkyl, cycloalkyl, andcycloalkenyl with the proviso that at least one of R R R and R ishydrogen and reacting in the presence of an alkaline condensing agent.

3. A process as in claim 2 in which the temperature of reaction is fromabout -20 C. to about 100 C.

4. A process as in claim 3 in which the alkaline condensing agent is aquaternary ammonium hydroxide.

5. A process for preparing2,2,5,5-thiophenetetrapropionitIile-1,1-dioxide which comprises reactingbutadiene sulfone with acrylonitrile in the presence of an alkalinecondensing agent.

6. 2,2,5,5-thiophenetetrapr-opionitrile-1,1-dioxide.

'7. 2,5 dimethyl-2,S-thiophenedipropionitrile-1,1-dioxide.

8. 2,5 diphenyl-Z,S-thiophenedipropionitrile-1,l-dioxide.

9. 3 methyl-2,2,5,5-thiophenetetrapropionitrile-1,l-dioxide.

10. 2-thiophenepropionitrile-1,1-dioxide.

11. A process as in claim 2 in which the reaction is conducted in anacetonitrile medium.

References Cited by the Examiner Asthema et al.: Iour. Indian Chem.Soc., Vol. 31 (1954), pages 459 and 460.

Bayer: Angew. Chemie, Vol. 61, No. 6 (1949), page 238.

Bruson: Organic Reactions, Wiley and Sons, New York, Vol. 5 (1949),pages and 81.

IRVING MARCUS, Primary Examiner.

NICHOLAS S. RIZZO, WALTER A. MODANCE,

. Examiners.

1. AN UNSATURATED SUBSTITUTED CYCLIC SULFONE OF THE FORMULA: